Uploaded September 2025 | Updated September 2026, 2 weeks ago

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Clem shows how to reverse engineer a cheap breathalyzer keyfob and repurpose it into an Arduino-compatible sensor module. By dissecting the circuit, discovering the LM339 comparator at its core, and reducing current draw by removing LEDs, he adapts the device for safe use with 3.3V logic microcontrollers like the Arduino MKR WiFi 1010. The project demonstrates how to integrate salvaged electronics into Arduino projects, including building voltage dividers for level shifting, handling warm-up delays, and logging sensor data. Follow along to learn techniques that can be applied to countless other gadgets. You can find the code and schematics on the e14 Community: bit.ly/4mElr7S

Visit the element14 Community for more great activities and free hardware:

Tech spotlights: bit.ly/3qPrDhM
RoadTest and Reviews: bit.ly/3pV5Bux
Project14: bit.ly/31wbnJY

Chapters:
02:01 - The Brief
05:02 - Reverse Engineering
07:03 - The Schematic
12:42 - The Logic
14:33 - Power up!
16:49 - The Arduino
18:44 - The Prototype
19:38 - The Code
22:39 - The Demo

#ArduinoProjects #ReverseEngineering #diyelectronics